1. Field of the Invention
The present invention relates to integrated circuits and, particularly, to a system and method for enabling functional units.
2. Description of the Related Art
Integrated processors are data processing devices having both a processor core and peripheral devices, or functional units, of various types. The processor core and the functional units are typically interconnected via a common bus. Because both the processor core and the functional units are implemented on a single integrated circuit, integrated processors are useful for cost sensitive control functions.
Integrated processors frequently operate in a variety of modes but may be customized for individual applications. For example, one or more functional units may be selected to be active. Such integrated processors typically have their modes customized through bits stored in nonvolatile memory. These bits are collectively referred to as the configuration register. The configuration bits can be programmed at the same time the on-chip non-volatile memory is programmed and thus the integrated processor may be customized for the application. The configuration bits form signals which are continuously driven to various circuits to select the operating modes.
Much of the cost savings associated with integrated processors is the ability to fabricate a plurality of functional units onto a single chip. Frequently, however, such functional units implement features developed by third party vendors. As such, the integrated processor manufacturer must typically pay a royalty for each chip produced. Often, however, not all of the on-chip functional units are enabled. In this case, it is undesirable for the chip manufacturer to pay a royalty for an unused functional unit. At the same time, however, the third party vendor desires confirmation of whether its functional unit is implemented on a chip before agreeing to accept a lower royalty or no royalty at all on that chip.
As such, there is a need for monitoring which functional units on an integrated processor are implemented.
These and other drawbacks in the prior art are overcome in large part by a system and method according to the present invention. Briefly, an integrated processor is provided having an integrated processor core. The processor core is configured to read configuration data and provide it to a configuration register. The configuration register enables various functional units also integrated onto the integrated processor. A tracking register is further provided, wherein the tracking register maintains a copy of the configuration data and a copy of the integrated processor""s version or serial number. The version number and the configuration data are provided to an external pin for monitoring.
Further, a checking circuit is provided to monitor that the external pin is not being externally overdriven. If it is, the functional units are all disabled. A CHECK control signal is provided to a tri-state output driver, which drives the check pin. When the tri-state output driver is active, the contents of the tracking register may be output via the pin. When the tri-state output driver is deactivated, a checking selection circuit monitors the condition of the pin. If the pin is being externally driven, a DISABLE control signal is generated.
A monitoring environment according to an embodiment of the present invention permits the collection of a database associating integrated processor serial numbers and activated or enabled functional units. The monitoring environment may further be used to check if particular integrated processors are, in practice, employing only the correct functional units.